What are Cicadas?

An illustration of cicada tymbals from
C.L. Marlatt's The Periodical Cicada. c shows the muscles and tendons connected to the tymbals, and d
& e show the bending of the tymbal.

Cicadas are insects, best known for the songs sung by most, but not all, male cicadas. Males sing by flexing their tymbals, which are drum-like organs found in their abdomens. Small muscles rapidly pull the tymbals in and out of shape. The sound is intensified by the cicada's mostly hollow abdomen. Female and some male cicadas will also make a sound by flicking their wings, but it isn't the same as the sound for which cicadas are known. Listen to some of the songs cicadas sing.

A Magicicada drinking from a tree. Photo by Roy Troutman.

Cicadas belong to the order Hemiptera, suborder Auchenorrhyncha, superfamily Cicadoidea and families Cicadidae (the vast majority of cicadas) or Tettigarctidae (only two species). Leafhoppers, spittle bugs and jumping plant lice are close relatives of the cicada. Hemiptera are different from other insects in that both the nymph and adult forms have a beak (aka rostrum), which they use to suck fluids called xylem from plants. This is how they both eat and drink.

Life Cycle

Cicadas begin life as a rice-shaped egg, which the female deposits in a groove she makes in a tree limb, using her ovipositor. The groove provides shelter and exposes the tree fluids, which the young cicadas feed on. These grooves can kill small branches. When the branches die and leaves turn brown, it is called flagging.

Once the cicada hatches from the egg it will begin to feed on the tree fluids. At this point it looks like a termite or small white ant. Once the young cicada is ready, it crawls from the groove and falls to the ground where it will dig until it finds roots to feed on. It will typically start with smaller grass roots and work its way up to the roots of its host tree. The cicada will stay underground from 2 to 17 years depending on the species. Cicadas are active underground, tunneling and feeding, and not sleeping or hibernating as commonly thought.

After the long 2 to 17 years, cicadas emerge from the ground as nymphs. Nymphs climb the nearest available tree, and begin to shed their nymph exoskeleton. Free of their old skin, their wings will inflate with fluid and their adult skin will harden. Once their new wings and body are ready, they can begin their brief adult life.

Adult cicadas, also called imagoes, spend their time in trees looking for a mate. Males sing, females respond, mating begins, and the cycle of life begins again.

Different Types of Life Cycles

There are three types of cicada life cycles:

Annual: Cicada species with annual life cycles emerge every year, for example, Swamp Cicadas (Neotibicen tibicen) emerge every year in the United States, and Green Grocers (Cyclochila australasiae) emerge every year in Australia.

Periodical: Cicadas species with periodical life cycles emerge all together after long periods of time, for example, Magicicada septendecim will emerge every 17 years (Find out where they'll emerge next).

Proto-periodical: Cicada species with proto-periodical life cycles might emerge every year, but every so many years they emerge in heavy numbers, like the Okanagana.

How Many Cicadas Are There?

There are over 190 varieties (including species & subspecies) of cicadas in North America, and over 3,390 varieties of cicadas around the world. This number grows each year as researchers discover and document new species. Cicadas exist on every continent but Antarctica.

The Largest Cicada:

The world's largest species of cicada is the Megapomponia imperatoria, which is native to Malaysia. The largest species in North America is Megatibicen auletes, aka the Northern Dusk Singing Cicada. Other notably large cicadas include the Bear Cicada of Japan (Cryptotympana facialis), and Tacua speciosa of south-east Asia.

The Loudest Cicadas:

The world's loudest cicada is the Brevisana brevis, a cicada found in Africa that reaches 106.7 decibels when recorded at a distance of 50cm (~20"), according to researcher John Petti.

The Megatibicen pronotalis walkeri (formerly known as Tibicen walkeri) is the loudest cicada in North America, and can achieve 105.9 decibels, measured at 50cm.

That said, Australian species of cicadas, like the Double Drummer (Thopa saccata) are said to approach 120 (deafening) decibels at close range. It is unknown how many decibels Thopa saccata can create at 50cm.

Longest Lifecycle:

The most well-known cicadas in the North America are the Magicicada periodical cicadas, aka "locusts", which have amazingly long 17 or 13 year lifecycles. Brood VII (17 year life cycle) will emerge in New York in 2018. Magicicada have been documented to emerge after 22 years. Read more: How long do cicadas live?